RS-232 to RS-485 Serial Communications Adapter

30020

$35.00 USD
Qty
Price
1
$35.00 ea.

RS-232 to RS-485 - sometimes you need the flexibility that a RS-485 gives you over the simple RS232!


Description [Hide]

Power Requirements
  Requires at least two RS-232 output handshake lines for power.
RS-232 Side
Connector: DB-9 female
Signals: Passes through pins 3 (TD) and 2 (RD). Pins 7 (RTS) and 8 (CTS) are tied together. Pins 4 (DTR), 6 (DSR), and 1 (CD) are tied together.
RS-485 Side
Connector: 3 pin terminal block
Signals: Half-duplex two-wire operation only. Automatic control circuit enables driver only when transmitting. Receiver is disabled when transmitting to prevent echo back to RS-232 device. Can transmit up to 4000 feet at 19,200 baud.
Dimensions
  2.75" x 1.25" x 0.6"
7cm x 3.2cm x 1.5cm
 
No handshaking is required to control the RS-485 driver. The handshake lines are required but only to provide power to the converter. The RS-485 driver is automatically enabled during each spacing state on the RS-232 side. During the marking or idle state, the RS-485 driver is disabled and the data lines are held in the marking state by pull-up and pull-down resistors.

The SCA-321 has an internal connection to prevent data transmitted from the RS-232 port from being echoed back to the RS-232 port. The SCA-321 is used as a two wire (half duplex) RS-485 converter with a third conductor to be used as signal ground. Using a common signal ground ensures that the common mode voltage between devices falls within the specifications of RS-485. This is especially important for networked devices with opto-isolated RS-485 interfaces.

Using the SCA-321 to communicate to most RS-485 devices does not usually require any termination. Termination is used to match impedance of a node to the impedance of the transmission line being used. When impedances are mismatched, the transmitted signal is not completely absorbed by the load and a portion is reflected back into the transmission line. This reflected signal can cause communication errors especially on long cable runs using a high data rate. If termination is required, the SCA-321 only supports AC coupled terminators. One terminator should be installed on each end of a straight cable run. A typical AC termination is a 120 Ohm resistor and a 0.1 uF capacitor in series between 485(+) and 485(-).

Documentation [Hide]

You Might Also Like [Hide]

SparkFun USB to RS-485 Converter

50572

This breakout board pairs an SP3485 RS-485 transceiver with an FT232RL USB UART IC to convert a USB stream to RS-485.

$19.95 USD


Arduino USB Board (Uno R3)

50450

The Arduino Uno is the all-new replacement for the favourite and popular Arduino Duemilanove. Now shipping R3!

$29.45 USD


EFX-Tek RS-485 Adapter

27280

The EFX-Tek RS-485 adapter is an ideal solution for putting multiple microcontrollers on a custom network.

$31.46 USD


Logic Level Converter

50550

The SparkFun logic level converter is a small device that safely steps down 5V signals to 3.3V and steps up 3.3V to 5V. This level converter also works with 2.8V and 1.8V devices.

$1.95 USD


Parallax USB to Serial RS-232 Adapter

21197

The Parallax USB to RS-232 is a great little adapter that takes your mini-USB connector and converts it to a RS-232 interface!

$14.95 USD


Sharp Analog Distance Sensor 20-150cm

35235

The Sharp line of analog infrared rangefinders are back, and with their usual high-level of noise and color immunity. These are great distance sensors that should be near the top of anybody's list for simple & effective obstacle detection!

$13.95 USD


Sparkfun WTV020SD Audio Breakout Board

50409

Convert your sound files to .AD4 and store them on an microSD card for instant audio playback. Either use a simple button control or two wire serial communication from a microcontroller to activate the sound files & play them through a speaker. This audio player is super small too!

$19.95 USD


Arduino Protoshield

50570

The Sparkfun Arduino protoshield as some very useful portable prototyping space that plugs onto the top of the popular Arduino / Freeduino SB.

$16.95 USD


SCC3733a-MSE Powerful Bundle 2

BSCC3733A-MSE-2

Need the parts to build up your SCC3733a-MSE? This package lets you assemble the Miller Solarengine in "Power" mode, where it stores up a lot of power, and releases a long burst to the motor.

$19.75 USD


The Solarbotics SketchBoard

28922

A fully assembled surface mount Arduino-compatible.

$17.50 USD


Currency


Login

Email:

Password:

Remember Me

Forgot Your Password?

Don't Have an Account?
Sign Up!